Charles Patrick Davis, MD, PhD

Dr. Charles "Pat" Davis, MD, PhD, is a board certified Emergency Medicine doctor who currently practices as a consultant and staff member for hospitals. He has a PhD in Microbiology (UT at Austin), and the MD (Univ. Texas Medical Branch, Galveston). He is a Clinical Professor (retired) in the Division of Emergency Medicine, UT Health Science Center at San Antonio, and has been the Chief of Emergency Medicine at UT Medical Branch and at UTHSCSA with over 250 publications.

William C. Shiel Jr., MD, FACP, FACR

Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.

What is homocysteine?

Homocysteine is an amino acid that is produced by the body by chemically
altering adenosine. Amino acids are naturally made products, which are the
building blocks of all the proteins in the body.

Can elevated homocysteine levels be genetic?

In 1969, Dr. Kilmer S. McCully reported that children born with a
genetic
disorder called homocystinuria, which causes the homocysteine levels to be very
high, sometimes died at a very young age with advanced atherosclerosis in their
arteries. Homocysteine levels in the blood may be elevated for many reasons.
More specifically, these reasons can be divided into severe genetic causes and
other milder causes.

In the genetic condition called homocystinuria, there is a deficiency or lack
of an important mediator molecule (enzymes) in the complicated homocysteine
breakdown pathway. This leads to severely elevated levels of homocysteine. In
this rare and serious condition, there is a constellation of symptoms that
include developmental delay, osteoporosis (thin bones), visual abnormalities,
formation of blood clots, and advanced atherosclerosis (narrowing and hardening
of blood vessels). This condition is mainly recognized in childhood.

Milder genetic variations are more common causes of elevated homocysteine
levels (hyperhomocysteinemia). In these conditions, the mediator molecules
malfunction and are less efficient because of minor abnormality in their
structure. They also lead to elevation of homocysteine levels, although much
milder than in homocystinuria, by slowing down the breakdown of homocysteine.